Table saw

ABSTRACT

Table saws and table saws designed to incorporate safety systems are disclosed. The table saws may include vertical slide elevation mechanisms positioned toward the rear of the saw and constructed so that an arbor block and blade can retract when a safety system detects an unsafe condition. Other table saw parts and components are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of and priority from the followingU.S. Provisional Patent Application, the disclosure of which is hereinincorporated by reference: Ser. No. 61/189,412, filed Aug. 18, 2008.

TECHNICAL FIELD

This specification relates to table saws and table saw components. Morespecifically, this specification relates to table saws designed toincorporate safety systems.

BACKGROUND

A table saw is a power tool used to cut a work piece to a desired sizeor shape. A table saw includes a work surface or table and a circularblade extending up through the table. A person uses a table saw byholding a work piece on the table and feeding it past the spinning bladeto make a cut. The table saw is one of the most basic machines used inwoodworking.

The blade of a table saw, however, presents a risk of injury to a userof the saw. If the user accidentally places their hand in the path ofthe blade, or if their hand slips or is conveyed into the blade, thenthe user could receive a serious injury or amputation. Accordingly,safety systems or features are often incorporated into table saws tominimize the risk of injury. One safety system detects a dangerouscondition between the user and the blade, such as proximity oraccidental contact with the blade, and then reacts to minimize anyinjury, such as by quickly stopping, retracting, and/or covering theblade.

The present document discloses table saws and table saw components. Thedisclosed table saws may incorporate a safety system as described.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic block diagram of a machine with a fast-actingsafety system.

FIG. 2 is a schematic diagram of an exemplary safety system in thecontext of a machine having a circular blade.

FIG. 3 shows a table saw.

FIG. 4 shows the cabinet of the table saw in FIG. 3 with the tabledetached.

FIG. 5 shows front and rear trunnion brackets in the cabinet of thetable saw in FIG. 3 with the table removed.

FIG. 6 shows the front and rear trunnion brackets of FIG. 5 isolatedfrom the saw.

FIG. 7 shows another view of the front and rear trunnion bracketsisolated from the saw.

FIG. 8 shows the front and rear trunnion brackets of FIG. 6 with frontand rear trunnions and torque tubes attached.

FIG. 9 shows another view of the front and rear trunnion brackets ofFIG. 6 with front and rear trunnions and torque tubes attached.

FIG. 10 shows the front trunnion of FIG. 8 isolated.

FIG. 11 shows the front trunnion with the sector gear detached.

FIG. 12 shows a tilt worm meshed with the sector gear of the fronttrunnion of FIG. 10 while the front trunnion is tilted.

FIG. 13 shows the tilt handwheel extending from the side of the saw ofFIG. 3.

FIG. 14 shows an elevation plate isolated from the saw.

FIG. 15 shows the elevation plate of FIG. 14 attached to the reartrunnion.

FIG. 16 shows the attachment of a threaded rod to the elevation plate ofFIG. 14.

FIG. 17 shows the attachment of elevation shafts to the rear trunnion.

FIG. 18 shows the elevation worm meshed with the worm gear at the backof the rear trunnion.

FIG. 19 shows an alternative elevation mechanism.

FIG. 20 shows a locking mechanism for a handwheel.

FIG. 21 shows an alternative elevation mechanism.

FIG. 22 shows the elevation mechanism of FIG. 21 in a lowered position.

FIG. 23 shows the elevation mechanism of FIG. 21 in a raised position.

FIG. 24 shows an alternative elevation mechanism using a chain andsprocket.

FIG. 25 shows another configuration of an elevation mechanism using achain and sprocket.

FIG. 26 shows an arbor block mounted on the elevation plate of FIG. 14.

FIG. 27 shows the arbor block of FIG. 26 isolated.

FIG. 28 shows a retraction bracket mounted on the elevation plate ofFIG. 14 alongside the arbor block of FIG. 26.

FIG. 29 shows another arbor block.

FIG. 30 shows a custom square head bolt.

FIG. 31 shows the arbor block of FIG. 29 with another retractionbracket.

FIG. 32 shows a motor and pulley assembly.

FIG. 33 shows a side view of the internal mechanism of the saw in FIG.3.

FIG. 34 shows another side view of the internal mechanism of the saw inFIG. 3.

FIG. 35 shows another view of the internal mechanism of the saw of FIG.3.

FIG. 36 shows a saw configuration using one belt to drive the arborshaft.

FIG. 37A shows a dust port.

FIG. 37B shows another view of the dust port in FIG. 37A.

FIG. 37C shows a side view of the dust port of FIG. 37A.

FIG. 38 shows the saw of FIG. 3 with a motor cover detached.

FIG. 39 shows the motor cover in FIG. 38 installed on the side of thesaw of FIG. 3.

FIG. 40 shows a portion of a hinge for the motor cover of FIG. 38.

FIG. 41 shows the motor cover of FIG. 38 isolated.

FIG. 42 shows another view of the motor cover of FIG. 38 isolated.

FIG. 43 shows a latch mechanism of the motor cover of FIG. 38.

DETAILED DESCRIPTION

A machine that incorporates a safety system to detect and react to adangerous condition, such as human contact with a designated portion ofthe machine, is shown schematically in FIG. 1 and indicated generally at10. Machine 10 may be any of a variety of different machines, such astable saws, miter saws, band saws, jointers, shapers, routers, hand-heldcircular saws, up-cut saws, sanders, etc. Machine 10 includes anoperative structure 12 having a working or cutting tool 14 and a motorassembly 16 adapted to drive the cutting tool. Machine 10 also includesa safety system 18 configured to minimize the potential of a seriousinjury to a person using the machine. Safety system 18 is adapted todetect the occurrence of one or more dangerous conditions during use ofthe machine. If such a dangerous condition is detected, safety system 18is adapted to engage operative structure 12 to limit any injury to theuser caused by the dangerous condition.

Machine 10 also includes a suitable power source 20 to provide power tooperative structure 12 and safety system 18. Power source 20 may be anexternal power source such as line current, or an internal power sourcesuch as a battery. Alternatively, power source 20 may include acombination of both external and internal power sources. Furthermore,power source 20 may include two or more separate power sources, eachadapted to power different portions of machine 10.

It will be appreciated that operative structure 12 may take any one ofmany different forms. For example, operative structure 12 may include astationary housing configured to support motor assembly 16 in drivingengagement with cutting tool 14. Alternatively, operative structure 12may include one or more transport mechanisms adapted to convey a workpiece toward and/or away from cutting tool 14.

Motor assembly 16 includes at least one motor adapted to drive cuttingtool 14. The motor may be either directly or indirectly coupled to thecutting tool, and may also be adapted to drive work piece transportmechanisms. The particular form of cutting tool 14 will vary dependingupon the various embodiments of machine 10. For example, cutting tool 14may be a single, circular rotating blade having a plurality of teethdisposed along the perimetrical edge of the blade. Alternatively, thecutting tool may be a plurality of circular blades, such as a dado bladeor dado stack, or some other type of blade or working tool.

Safety system 18 includes a detection subsystem 22, a reaction subsystem24 and a control subsystem 26. Control subsystem 26 may be adapted toreceive inputs from a variety of sources including detection subsystem22, reaction subsystem 24, operative structure 12 and motor assembly 16.The control subsystem may also include one or more sensors adapted tomonitor selected parameters of machine 10. In addition, controlsubsystem 26 typically includes one or more instruments operable by auser to control the machine. The control subsystem is configured tocontrol machine 10 in response to the inputs it receives.

Detection subsystem 22 is configured to detect one or more dangerous ortriggering conditions during use of machine 10. For example, thedetection subsystem may be configured to detect that a portion of theuser's body is dangerously close to or in contact with a portion ofcutting tool 14. As another example, the detection subsystem may beconfigured to detect the rapid movement of a work piece due to kickbackby the cutting tool, as is described in U.S. Pat. No. 7,055,417, thedisclosure of which is herein incorporated by reference. In someembodiments, detection subsystem 22 may inform control subsystem 26 ofthe dangerous condition, which then activates reaction subsystem 24. Inother embodiments, the detection subsystem may be adapted to activatethe reaction subsystem directly.

Once activated in response to a dangerous condition, reaction subsystem24 is configured to engage operative structure 12 quickly to preventserious injury to the user. It will be appreciated that the particularaction to be taken by reaction subsystem 24 will vary depending on thetype of machine 10 and/or the dangerous condition that is detected. Forexample, reaction subsystem 24 may be configured to do one or more ofthe following: stop the movement of cutting tool 14, disconnect motorassembly 16 from power source 20, place a barrier between the cuttingtool and the user, or retract the cutting tool from its operatingposition, etc. The reaction subsystem may be configured to take acombination of steps to protect the user from serious injury. Placementof a barrier between the cutting tool and teeth is described in moredetail in U.S. Patent Application Publication No. 2002/0017183 A1,entitled “Cutting Tool Safety System,” the disclosure of which is hereinincorporated by reference. Retracting the cutting tool is described inmore detail in U.S. Patent Application Publication No. 2002/0017181 A1,entitled “Retraction System for Use in Power Equipment,” and U.S. PatentApplication Publication No. 2004/0173430 A1, entitled “Retraction Systemand Motor Position for Use With Safety Systems for Power Equipment,” thedisclosures of which are herein incorporated by reference.

The configuration of reaction subsystem 24 typically will vary dependingon which action or actions are taken. In the exemplary embodimentdepicted in FIG. 1, reaction subsystem 24 is configured to stop themovement of cutting tool 14 and includes a brake mechanism 28, a biasingmechanism 30, a restraining mechanism 32, and a release mechanism 34.Brake mechanism 28 is adapted to engage operative structure 12 under theurging of biasing mechanism 30. During normal operation of machine 10,restraining mechanism 32 holds the brake mechanism out of engagementwith the operative structure. However, upon receipt of an activationsignal by reaction subsystem 24, the brake mechanism is released fromthe restraining mechanism by release mechanism 34, whereupon, the brakemechanism quickly engages at least a portion of the operative structureto bring the cutting tool to a stop.

It will be appreciated by those of skill in the art that the exemplaryembodiment depicted in FIG. 1 and described above may be implemented ina variety of ways depending on the type and configuration of operativestructure 12. Turning attention to FIG. 2, one example of the manypossible implementations of safety system 18 is shown. System 18 isconfigured to engage an operative structure having a circular blade 40mounted on a rotating shaft or arbor 42. Blade 40 includes a pluralityof cutting teeth (not shown) disposed around the outer edge of theblade. As described in more detail below, braking mechanism 28 isadapted to engage the teeth of blade 40 and stop the rotation of theblade. U.S. Patent Application Publication No. 2002/0017175 A1, entitled“Translation Stop For Use In Power Equipment,” the disclosure of whichis herein incorporated by reference, describes other systems forstopping the movement of the cutting tool. U.S. Patent ApplicationPublication No. 2002/0017184 A1, entitled “Table Saw With ImprovedSafety System,” U.S. Patent Application Publication No. 2002/0017179 A1,entitled “Miter Saw With Improved Safety System,” U.S. PatentApplication Publication No. 2002/0059855 A1, entitled “Miter Saw withImproved Safety System,” U.S. Patent Application Publication No.2002/0056350 A1, entitled “Table Saw With Improved Safety System,” U.S.Patent Application Publication No. 2002/0059854 A1, entitled “Miter SawWith Improved Safety System,” U.S. Patent Application Publication No.2002/0056349 A1, entitled “Miter Saw With Improved Safety System,” U.S.Patent Application Publication No. 2002/0056348 A1, entitled “Miter SawWith Improved Safety System,” and U.S. Patent Application PublicationNo. 2002/0066346 A1, entitled “Miter Saw With Improved Safety System,”U.S. Patent Application Publication No. 2003/0015253 A1, entitled“Router With Improved Safety System,” U.S. Patent ApplicationPublication No. 2002/0170400 A1, entitled “Band Saw With Improved SafetySystem,” U.S. Patent Application Publication No. 2003/0019341 A1,entitled “Safety Systems for Band Saws,” U.S. Patent ApplicationPublication No. 2003/0056853 A1, entitled “Router With Improved SafetySystem,” U.S. Patent Application Publication No. 2004/0040426 A1,entitled “Miter Saw With Improved Safety System,” U.S. PatentApplication Publication No. 2005/0039822 A1, entitled “WoodworkingMachines With Overmolded Arbors,” U.S. Patent Application PublicationNo. 2005/0139057 A1, entitled “Table Saws With Safety Systems,” U.S.Patent Application Publication No. 2005/0166736 A1 entitled “Table SawsWith Safety Systems and Systems to Mount and Index Attachments,” andU.S. Patent Application Publication No. 2005/0178259 A1, entitled “MiterSaw With Improved Safety System,” the disclosures of which are hereinincorporated by reference, describe or relate to safety system 18 in thecontext of particular types of machines.

In the exemplary implementation, detection subsystem 22 is adapted todetect the dangerous condition of the user coming into contact withblade 40. The detection subsystem includes a sensor assembly, such ascontact detection plates 44 and 46, capacitively coupled to blade 40 todetect any contact between the user's body and the blade. Typically, theblade, or some larger portion of cutting tool 14 is electricallyisolated from the remainder of machine 10. Alternatively, detectionsubsystem 22 may include a different sensor assembly configured todetect contact in other ways, such as optically, resistively, etc. Inany event, the detection subsystem is adapted to transmit a signal tocontrol subsystem 26 when contact between the user and the blade isdetected. Various exemplary embodiments and implementations of detectionsubsystem 22 are described in more detail in U.S. Patent ApplicationPublication No. 2002/0017176 A1, entitled “Detection System For PowerEquipment,” U.S. Patent Application Publication No. 2002/0017336 A1,entitled “Apparatus And Method For Detecting Dangerous Conditions InPower Equipment,” U.S. Patent Application Publication No. 2002/0069734A1, entitled “Contact Detection System for Power Equipment,” U.S. PatentApplication Publication No. 2002/0190581 A1, entitled “Apparatus andMethod for Detecting Dangerous Conditions in Power Equipment,” U.S.Patent Application Publication No. 2003/0002942 A1, entitled “DiscreteProximity Detection System,” U.S. Patent Application Publication No.2003/0090224 A1, entitled “Detection System for Power Equipment,” andU.S. Provisional Patent Application Publication No. 2005/0155473 A1,entitled “Improved Detection Systems for Power Equipment,” thedisclosures of which are all herein incorporated by reference.

Control subsystem 26 includes one or more instruments 48 that areoperable by a user to control the motion of blade 40. Instruments 48 mayinclude start/stop switches, speed controls, direction controls,light-emitting diodes, etc. Control subsystem 26 also includes a logiccontroller 50 connected to receive the user's inputs via instruments 48.Logic controller 50 is also connected to receive a contact detectionsignal from detection subsystem 22. Further, the logic controller may beconfigured to receive inputs from other sources such as blade motionsensors, work piece sensors, etc. In any event, the logic controller isconfigured to control operative structure 12 in response to the user'sinputs through instruments 48. However, upon receipt of a contactdetection signal from detection subsystem 22, the logic controlleroverrides the control inputs from the user and activates reactionsubsystem 24 to stop the motion of the blade. Various exemplaryembodiments and implementations of control subsystem 26, and componentsthat may be used in control system 26, are described in more detail inU.S. Patent Application Publication No. 2002/0020262 A1, entitled “LogicControl For Fast-Acting Safety System,” U.S. Patent ApplicationPublication No. 2002/0017178 A1, entitled “Motion Detecting System ForUse In Safety System For Power Equipment,” U.S. Patent ApplicationPublication No. 2003/0058121 A1, entitled “Logic Control With Test Modefor Fast-Acting Safety System,” U.S. Provisional Patent ApplicationPublication No. 2005/0041359 A1, entitled “Motion Detecting System foruse in a Safety System for Power Equipment,” and U.S. Provisional PatentApplication Publication No. 2005/0139459 A1, titled “Switch Box forPower Tools with Safety Systems,” the disclosures of which are allherein incorporated by reference.

In the exemplary implementation, brake mechanism 28 includes a pawl 60mounted adjacent the edge of blade 40 and selectively moveable to engageand grip the teeth of the blade. Pawl 60 may be constructed of anysuitable material adapted to engage and stop the blade. As one example,the pawl may be constructed of a relatively high strength thermoplasticmaterial such as polycarbonate, ultrahigh molecular weight polyethylene(UHMW) or Acrylonitrile Butadiene Styrene (ABS), etc., or a metal suchas fully annealed aluminum, etc. It will be appreciated that theconstruction of pawl 60 may vary depending on the configuration of blade40. In any event, the pawl is urged into the blade by a biasingmechanism in the form of a spring 66. In the illustrative embodimentshown in FIG. 2, pawl 60 is pivoted into the teeth of blade 40. Itshould be understood that sliding or rotary movement of pawl 60 mightalso be used. The spring is adapted to urge pawl 60 into the teeth ofthe blade with sufficient force to grip the blade and quickly bring itto a stop.

The pawl is held away from the edge of the blade by a restrainingmechanism in the form of a fusible member 70. The fusible member isconstructed of a suitable material adapted to restrain the pawl againstthe bias of spring 66, and also adapted to melt under a determinedelectrical current density. Examples of suitable materials for fusiblemember 70 include NiChrome wire, stainless steel wire, etc. The fusiblemember is connected between the pawl and a contact mount 72. Preferably,fusible member 70 holds the pawl relatively close to the edge of theblade to reduce the distance the pawl must travel to engage the blade.Positioning the pawl relatively close to the edge of the blade reducesthe time required for the pawl to engage and stop the blade. Typically,the pawl is held approximately 1/32-inch to ¼-inch from the edge of theblade by fusible member 70, however other pawl-to-blade spacings mayalso be used.

Pawl 60 is released from its unactuated, or cocked, position to engageblade 40 by a release mechanism in the form of a firing subsystem 76.The firing subsystem is coupled to contact mount 72, and is configuredto melt fusible member 70 by passing a surge of electrical currentthrough the fusible member. Firing subsystem 76 is coupled to logiccontroller 50 and activated by a signal from the logic controller. Whenthe logic controller receives a contact detection signal from detectionsubsystem 22, the logic controller sends an activation signal to firingsubsystem 76, which melts fusible member 70, thereby releasing the pawlto stop the blade. Various exemplary embodiments and implementations ofreaction subsystem 24 are described in more detail in U.S. PatentApplication Publication No. 2002/0020263 A1, entitled “Firing SubsystemFor Use In A Fast-Acting Safety System,” U.S. Patent ApplicationPublication No. 2002/0020271 A1, entitled “Spring-Biased Brake Mechanismfor Power Equipment,” U.S. Patent Application Publication No.2002/0017180 A1, entitled “Brake Mechanism For Power Equipment,” U.S.Patent Application Publication No. 2002/0059853 A1, entitled “Power SawWith Improved Safety System,” U.S. Patent Application Publication No.2002/0020265 A1, entitled “Translation Stop For Use In Power Equipment,”U.S. Patent Application Publication No. 2003/0005588 A1, entitled“Actuators For Use in Fast-Acting Safety Systems,” and U.S. PatentApplication Publication No. 2003/0020336 A1, entitled “Actuators For UseIn Fast-Acting Safety Systems,” the disclosures of which are hereinincorporated by reference.

It will be appreciated that activation of the brake mechanism willrequire the replacement of one or more portions of safety system 18. Forexample, pawl 60 and fusible member 70 typically must be replaced beforethe safety system is ready to be used again. Thus, it may be desirableto construct one or more portions of safety system 18 in a cartridgethat can be easily replaced. For example, in the exemplaryimplementation depicted in FIG. 2, safety system 18 includes areplaceable cartridge 80 having a housing 82. Pawl 60, spring 66,fusible member 70 and contact mount 72 are all mounted within housing82. Alternatively, other portions of safety system 18 may be mountedwithin the housing. In any event, after the reaction system has beenactivated, the safety system can be reset by replacing cartridge 80. Theportions of safety system 18 not mounted within the cartridge may bereplaced separately or reused as appropriate. Various exemplaryembodiments and implementations of a safety system using a replaceablecartridge, and various brake pawls, are described in more detail in U.S.Patent Application Publication No. 2002/0020261 A1, entitled“Replaceable Brake Mechanism For Power Equipment,” U.S. PatentApplication Publication No. 2002/0017182 A1, entitled “Brake PositioningSystem,” U.S. Patent Application Publication No. 2003/0140749 A1,entitled “Brake Pawls for Power Equipment,” and U.S. Patent ApplicationPublication No. 2005/0039586 A1, entitled “Brake Cartridges for PowerEquipment,” the disclosures of which are herein incorporated byreference.

While one particular implementation of safety system 18 has beendescribed, it will be appreciated that many variations and modificationsare possible. Many such variations and modifications are described inU.S. Patent Application Publication No. 2002/0170399 A1, entitled“Safety Systems for Power Equipment,” U.S. Patent ApplicationPublication No. 2003/0037651, entitled “Safety Systems for PowerEquipment,” and U.S. Patent Application Publication No. 2003/0131703 A1,entitled “Apparatus and Method for Detecting Dangerous Conditions inPower Equipment,” the disclosures of which are herein incorporated byreference.

A table saw adapted to implement features of the safety systemsdescribed above is shown at 100 in FIG. 3. Saw 100 is often called acabinet saw or a tilting-arbor saw. The saw includes a table 102 onwhich a work piece may be cut. The table is supported by a cabinet 104.A blade 106 (shown in FIG. 38) extends up through a slot in a tableinsert 107 which is fitted into an opening 108 in the table and a bladeguard 110 covers the blade. Handwheels 112 and 114 may be turned toadjust the elevation of the blade (the height the blade extends abovethe table) and the tilt of the blade relative to the tabletop,respectively. In operation, a user turns the handwheels to position theblade as desired and then makes a cut by pushing a work piece on thetable past the spinning blade.

FIGS. 4 and 5 show external views of saw 10. FIGS. 6 through 36 showvarious components and views of the internal mechanism of the saw. Theremaining figures show components and accessories that mount externallyto the saw. While saw 100 is adapted to implement features of the safetysystems described above, its construction and other features are uniqueand have utility separate from the safety systems. Many of thesefeatures and the construction of saw 100 are also applicable to sawsthat do not include safety systems as described above.

In saw 100, table 102 is bolted onto cabinet 104 by four bolts 120, asshown in FIG. 4. The cabinet is constructed to support the weight ofboth the table and the internal mechanism of the saw. There are fourmetal plates 122 welded to the top of the cabinet such that each platelies horizontally adjacent a corner of the cabinet. Each bolt 120 passesthrough a fender washer 124 and then through an oversized hole 126 in ametal plate 122. As will be discussed below, holes 126 are oversized sothat when the bolts are loosened some adjustment can be made in theposition of the table with regard to the cabinet. Each bolt then screwsinto a threaded hole 128 in the underside of table 102. Metal plates 122at the front corners of the cabinet extend outward from the cabinet sothat the bolts 120 at the front of the cabinet are accessible. Bolts 120in the back of the cabinet can be accessed through a cut-out 130 on theright side of the cabinet and through a cut-out 132 on the left side ofthe cabinet under a cover 900, as shown in FIG. 4. In thisimplementation, table 102 is secured to the cabinet, but the table couldbe secured directly to the internal mechanism of the saw or to someother support instead of the cabinet.

Also bolted to metal plates 122 at the front of the cabinet is a fronttrunnion bracket 140, as shown in FIG. 5, which shows cabinet 104 withthe table removed. A rear trunnion bracket 142 is bolted to metal plates122 at the back of the cabinet. Each bolt 144 passes upward through alock washer 146, a washer 148, and an oversized hole 150 in a metalplate 122. Each bolt then threads into a hole 152 at the top of eachtrunnion bracket, one hole on each side of each bracket. The front andrear trunnion brackets 140 and 142 form part of the internal mechanismof the saw and support the rest of the internal mechanism. Duringassembly, the internal mechanism of the saw, including the front andrear trunnion brackets, is lowered into the cabinet. Two positioningpins 154 are press-fitted into the underside of the rear trunnionbracket and serve to guide the positioning of the internal mechanism asit is placed into the cabinet. The positioning pins fit, respectively,into corresponding hole 156, which is oval, and hole 158, which iscircular, in the metal plates 122 on the back left and right corners ofthe saw. Hole 158 is circular to provide precise positioning while hole156 is oval to allow for manufacturing tolerances. The front and reartrunnion brackets are shown isolated from the saw in FIGS. 6 and 7.

It is important for table 102 to be positioned properly relative to theblade. Typically, the front edge of the table should be as perpendicularto the plane of the blade as possible in order to make straight, squarecuts. There are many mechanisms by which the position of the tablerelative to the blade can be adjusted. One such mechanism includes a pin200 which extends up from a flange in front trunnion bracket 140, asshown in FIG. 4. That pin is positioned substantially in theside-to-side center of the front trunnion bracket. Pin 200 extends upinto a corresponding socket 202 in a bracket 204 which is bolted on theunderside of the front edge of the table. Table 102 is able to pivotaround the pin 200 when bolts 120 are loosened or absent. Table 102includes two holes 212, one in the right rear side of the table and onein the left rear side, as shown in FIG. 4. A positioning screw 214 isthreaded into each of those holes and extends through the side of thetable. Holes 212 are positioned so that when the positioning screws arethreaded through the holes, the ends of the bolts each abut the verticalwall of a U-shaped bracket 216 welded to each of the metal plates 122 atthe back right and left corners of the cabinet, respectively. Threadinga positioning screw farther into its hole will cause the positioningscrew to push against a bracket 216 and the table will then pivot aroundpin 200. Thus, the position or squareness of the table relative to theblade can be adjusted by threading each positioning screw into itscorresponding hole 212 by the amount necessary to pivot the table aroundpin 200 until the blade is parallel to the miter slots.

Saw 100 also includes front and rear trunnions 240 and 242. Thesetrunnions are supported in the saw by the front and rear trunnionbrackets, respectively, as shown in FIGS. 8 and 9. Each trunnion bracketincludes an arcuate groove or channel 244 (best seen in FIGS. 6 and 7),and the front and rear trunnions each include a corresponding arcuatetongue or flange 246 (labeled in FIGS. 8 and 9). Trunnion brackets 140and 142 support trunnions 240 and 242 by grooves 244 receivingcorresponding tongues 246. Alternatively, the tongues and grooves couldbe reversed so the trunnion brackets include the tongues and thetrunnions include the grooves. In this manner, the flanges provide ashoulder or surface on which the trunnions may rest. The arcuate tongueand groove connections also allow the trunnions to slide relative to thetrunnion brackets. When the trunnions slide on the trunnion brackets,the blade of the saw tilts relative to the tabletop because the blade issupported by the trunnions, as will be explained below. (The outline orshape of the trunnions and other parts described below may change fromwhat is shown in the figures to minimize material and/or weight.)

Two torque tubes, 260 and 262, extend between the front and reartrunnions so that the trunnions move together, as shown in FIGS. 8 and9. Torque tube 260 is the primary or main torque tube. It is a hollowtube with a two inch diameter and is sufficiently rigid to stabilize andconnect the front and rear trunnions without twisting. Four bolts 264,each with lock washers, are used at each end of torque tube 260 to boltit to the front and rear trunnions, respectively. Torque tube 262 is asecondary torque tube to further stabilize the trunnions. The secondarytorque tube is hollow and also functions as a protective casing for anelevation control shaft 524 which runs through the tube and which willbe discussed later. Four bolts 266 are used to bolt one end of torquetube 262 to the rear trunnion, as shown in FIG. 8. The other end oftorque tube 262 is welded to a rigid and vertical plate 268 whichextends upwards and bolts to front trunnion 240 with three bolts 270, asshown in FIG. 9. The torque tubes hold the front and rear trunnionssquare and prevent the trunnions from moving off flanges 244 when themechanism is assembled.

Torque tubes 260 and 262 are positioned to provide clearance for thearbor block and blade to retract, as discussed later. Additionally, thesecondary torque tube 262 is positioned low enough to provide clearancefor operating elevation handwheel 112 which mounts to the end ofelevation control shaft 524 so that a user turning the elevationhandwheel will not hit their knuckles on the underside of the table ofthe saw.

The trunnions and torque tubes are tilted relative to the trunnionbrackets by gears. A sector gear 300 is bolted to the front trunnionsuch that it runs along the arced bottom edge of the trunnion, as shownin FIG. 10. Two positioning pins 302 are press-fit into holes in thefront trunnion and fit into corresponding holes 310 and 312 in thesector gear, as shown in FIG. 11. The positioning pins are used to setthe position of the sector gear relative to the front trunnion. Hole 310on the sector gear has a circular shape corresponding to pin 302 whilehole 312 has an oval shape to allow for tolerances in the manufacturingof the sector gear. Designing the holes in this way ensures enoughleeway that the sector gear will match up with positioning pins 302 onthe front trunnion while maintaining as much accuracy as possible in thepositioning of the sector gear. Once positioned, the sector gear isbolted onto the front trunnion with two bolts. Each bolt 314 each passesthrough a lock washer 315, then through an oversized hole 316 in thesector gear and is threaded into a hole 318 in the front trunnion. Theoversized holes 316 in the sector gear allow the sector gear to fit ontothe front trunnion despite slight variations in the manufacturing of theparts. In this embodiment, the sector gear is bolted to the fronttrunnion so that if a tooth of the sector gear breaks the sector gearcan be replaced without having to replace the front trunnion.Alternatively, the front trunnion can be designed to include the sectorgear with the gear teeth cut into the front trunnion to minimize parts.

Sector gear 300 meshes with a worm 330 which is mounted at the end of ashaft 332, as shown in FIG. 12. A pin 334 threads perpendicularly intothe worm and then into shaft 332 to attach the worm to the shaft. Thetip of shaft 332 just beyond the worm fits into a bore in a bracket 336and a bolt 337 and washer hold it in place. A positioning pin 338 on thefront trunnion bracket (shown in FIG. 9) fits into an oversized hole atthe back of bracket 336 and bracket 336 is bolted onto front trunnionbracket 120 by bolts 340 which pass through oversized holes in bracket336 and thread into holes 342 in the front trunnion bracket. Of course,the oversized holes may be in the front trunnion bracket and thethreaded holes may be in bracket 336. The oversized holes allow foradjustment of the position of bracket 336 up or down relative to thefront trunnion. A set screw 344 threads into a hole 346 (shown in FIG.9) on a flange 347 at the bottom of front trunnion bracket 140underneath bracket 336. The head of the set screw is exposed and thethreaded end abuts the bottom of bracket 336. Threading set screw 344farther into hole 346 causes bracket 336 to be pushed upwards. Beingable to adjust the position of the bracket up or down allows adjustmentso that the sector gear meshes properly with the worm.

Shaft 332 extends out through a hole in the side of cabinet 104 andthrough a bushing 348 fitted within a bracket 350 that is attached tothe cabinet, as shown in FIG. 13. Bracket 350 is bolted to the side ofthe cabinet with two bolts, the head of which fit within hexagonal headshaped indentations 351 in the bracket. This aids in assembling the sawsince the indentations hold the bolts in place as the assembler supportsshaft 332 with one hand and tightens the nuts on each bolt with theother. A handwheel 114 is mounted on the end of the shaft. When a userturns handwheel 114 and thus shaft 332, worm 330 crawls along sectorgear 300 causing the trunnions and torque tubes to move and the blade totilt relative to the tabletop. As shown in FIG. 12, bracket 336 includesan arm 352 that overlaps sector gear 330 opposite the front trunnion tohelp prevent the bottom of front trunnion 240 from moving away from thefront trunnion bracket and to help maintain the sector gear in position.In addition, an arced protrusion 354 on the front trunnion bracket runsalongside the side of the sector gear opposite arm 352 on bracket 336 tokeep the sector gear within an area between protrusion 354 and arm 352.

Stops 360 and 368, labeled in FIGS. 10 and 11, limit the distance thatthe trunnions and torque tubes may move. Stop 360 comprises a bolt 362and a lock nut 366 to hold the bolt in place so that the threaded end ofthe bolt extends out from the back side of a shoulder 364. Bolt 362 isthreaded into and through a hole in shoulder 364 in the front trunnion.Bolt 362 and shoulder 364 are positioned so that the threaded end of thebolt will abut the side of the front trunnion bracket when the fronttrunnion is at the minimum tilt limit of its movement, as shown in FIG.9. Stop 368 comprises a bolt 370 threaded into a hole in edge 372 in thefront trunnion. A lock nut 374 holds the bolt in place. Bolt 370 ispositioned and edge 372 is angled so that the head of the bolt will abutthe underside of a shoulder 373 at the top of the front trunnion bracket(as shown in FIG. 9) when the front trunnion is at the maximum tiltlimit of its movement. The distance the trunnions may tilt can beadjusted by threading the bolts 362 and 370 in or out, as desired. Ofcourse, bolt 370 could be positioned in shoulder 373, in which case edge372 would abut the bolt, or bolt 370 could be positioned in otherlocations.

Saw 100 typically includes a label 374 mounted on the front of thecabinet as shown in FIG. 3. Label 374 includes angle demarcations toindicate the degree the blade tilts relative to the tabletop. A tiltindicator 376 (shown best in FIGS. 28 and 33) consisting of a narrowstrip of metal with two right-angle bends is bolted at one end to acollar 538 (labeled in FIG. 28) which is mounted on a shaft 524 thatextends between the front and rear trunnions and tilts along with themas discussed below. The other end of tilt indicator 376 passes through acurved slot 378 on the front of the cabinet, and is used to point to theangle demarcations on label 374. For instance, when the blade is tilted45 degrees relative to the tabletop, pointer 376 would point to the 45degree mark on label 374.

Saw 100 also includes an elevation plate 380 shown isolated in FIG. 14.The elevation plate is supported by the rear trunnion, as shown in FIG.15, and tilts with the front and rear trunnions. The blade is supportedon the elevation plate, as will be described, so tilting the elevationplate causes the blade to tilt. The elevation plate is also configuredto move up and down relative to the trunnions. Moving the elevationplate up and down is what causes the blade to move up and down relativeto table 102. The underside of table 102 may include recesses to allowthe blade to rise to a predetermined height without the internalmechanism of the saw bumping into the underside of the table.

Elevation plate 380 is supported in the saw by a shaft 390 that isoriented vertically at the left side of the elevation plate. Theelevation plate includes bores 382 and 384, situated at the top andbottom of the elevation plate, respectively, as shown best in FIG. 16.Shaft 390 supports the elevation plate by passing through these bores. Aflanged bushing 388, which may be made from oil impregnated bronze ordiluted bronze, is press-fitted into each of the bores and the bushingsprovide smooth surfaces so that the elevation plate can slide up anddown on the shaft. Shaft 390 is bolted onto rear trunnion 242 to holdthe elevation plate to the rear trunnion. In the depicted embodiment,shaft 390 fits into two notches 392 in rear trunnion 242 that haveangled sides to contact the cylindrical surface of the shaft and centerthe shaft in the notches, as shown in FIG. 17. Each notch has a threadedhole 396 in the center. One notch is located above the top bushing 388and the other notch is located above the bottom busing 388. Two bolts394 each pass through a lock washer 393, then through a hole 395 inshaft 390 and then thread into a hole 396 at the center of each notch392 in the rear trunnion. One of the holes 395 is located towards thetop of shaft 390 and the other near the middle of the shaft to supportthe shaft in a cantilever position so that the top bushing 388 slidesalong the shaft between the two holes 395 and the bottom bushing 388slides along the shaft below the hole 395 that is near the middle of theshaft. Shaft 390 is sufficiently rigid and sized so that thecantilevered lower portion of the shaft does not flex as elevation plate380 slides along the shaft. Flat areas are carved into the surface ofshaft 390 where bolts 394 pass through so that washers 393 may lie flatagainst the shaft. In this manner the shaft is securely anchored to therear trunnion.

Elevation plate 380 is also supported by a second shaft 398 located onthe right side of the elevation plate and running parallel to shaft 390.This second shaft passes through a bore 386 which is also fitted with aflanged bushing 388, as shown in FIG. 16. Shaft 398 fits into bore 386and is bolted to the rear trunnion by two long, thin bolts 400. Eachbolt 400 threads into a hole 404 in the rear trunnion, passes through adeep nut 402 which acts as a standoff, then extends through shaft 398,where it is secured with a nut 406, as shown in FIG. 17. It is importantthat elevation plate 380 be restricted from any side-to-side motion orrotation around the longitudinal axis of shaft 390 in order to hold thesaw blade straight. Generally, the presence of shaft 398 restrictsrotation about shaft 390 but over time and because of manufacturingtolerances in shafts 390 and 398 and their corresponding bores in theelevation plate, some adjustment may need to be made to ensure that theelevation plate is squared with the trunnions. This adjustment can bemade by tightening or loosening the long, thin bolts 400 that attachshaft 398 to the rear trunnion.

Elevation plate 380 is free to slide up and down on shafts 390 and 398.Ideally, shafts 390 and 398 would be parallel to each other so thatthere is no binding as the elevation plate moves up and down. Inreality, however, this is difficult to achieve due to variabilityinherent in the manufacturing and assembly processes. Thus, it isimportant to be able to adjust the orientation of the shafts relative toeach other. This is accomplished by the two long, thin bolts 400. Thelength of these bolts allow the distance between each end of shaft 398and the rear trunnion to be adjusted individually by repositioning nuts406 so that shaft 398 can be set coplanar to shaft 390. The deep nuts402 aid the user of the saw in adjusting bolts 400 by setting a fixed,repeatable minimum distance each end of the shaft may be from the reartrunnion. The user first rotates nuts 402 and 406 so that the shaft isclosest to the rear trunnion and coplanar with the primary elevationshaft 390. Then the user turns each deep nut 402 the same number ofturns to move each end of the shaft away from the rear trunnion by thesame distance. The thinness of bolts 400 also allows some adjustment inthe orientation of the elevation shafts relative to each other.Specifically, the thinness of bolts 400 allows them to flex slightlysideways (toward or away from shaft 390) as needed to allow the shaftsto remain parallel within their common plane as the elevation platemoves up and down.

The distance elevation plate 380 may slide up and down on shafts 390 and398 is ultimately defined by the spacing between notches 392 on the reartrunnion and the spacing between bores 382 and 384 on the elevationplate. That distance, however, may be further defined by adjustablestops 420 and 422 shown in FIGS. 15, 16 and 17. Stop 420 comprises abolt 424 threaded through a shoulder 426 in the elevation plate and alock nut 428 to hold the bolt in place, as shown in FIG. 16. The bolt ispositioned so that the threaded end of the bolt will abut the undersideof the rear trunnion at the limit of the upward movement of theelevation plate, as shown at area 430 in FIG. 15. As shown in FIG. 17,stop 422 comprises a bolt 432 threaded through a shoulder 434 in therear trunnion and a lock nut 436 to hold the bolt in place. This bolt ispositioned so that the threaded end of the bolt will abut underside 438(labeled in FIG. 15) of the elevation plate at the limit of the downwardmovement of the elevation plate. The distance the elevation plate mayslide up or down is thus defined by how far the stops or bolts extend.

A threaded rod 460, which acts as a rack, is bolted vertically along theleft side of elevation plate 380 by bolts 462, as shown in FIGS. 15 and16. The weight of the elevation plate and all the parts supported by theelevation plate is primarily supported by the threaded rod. Thus,threaded rod 460 is positioned close to the side-to-side center ofgravity of the elevation plate and all the parts it supports. Each bolt462 passes through a lock washer 464, a washer 466, and an oversizedhole in the threaded rod, one located towards the top of the threadedrod and the other near the bottom. The oversized holes allow for someadjustment in the position of the threaded rod as described below. Bolts462 then thread into holes 470 in the side of the elevation plate. Flatareas are cut into the surface of the threaded rod where the bolts passthrough so that the washers may lie flat against the threaded rod andthe threaded rod can lie flat against the elevation plate.

Threaded rod 460 meshes with a pinion gear 480 mounted on the back ofthe rear trunnion, as shown in FIG. 18. Two set screws 472, shown inFIG. 15, thread through the elevation plate at holes 474 and press upagainst flat areas at the top and bottom of the threaded rod. The setscrews are oriented at right angles to bolts 462 so that the set screwspoint towards the back of the saw. The inset hex heads of the set screwsare exposed so that the set screws can be screwed into the holes inorder to push the threaded rod more towards the back of the saw. Theadjustable set screws 472 provide a way to keep the threaded rod meshedwith the pinion gear.

Pinion gear 480 resides at one end of a short shaft 482 which extendsthrough two adjustable brackets 484 and 486 that are bolted to the backof the rear trunnion, as shown in FIG. 18. A flanged bushing 488 fitswithin a bore 490 in each of the brackets and the shaft passes throughthe bushings. A positioning pin on the back of each bracket is insertedinto a corresponding hole in the rear trunnion. The positioning pin ofbracket 484 fits into hole 500 and the positioning pin of bracket 486fits into hole 502 (shown in FIG. 9). Bolts 492 pass through oversizedholes in the brackets and thread into holes 496 the rear trunnion (shownin FIG. 9). Brackets 484 and 486 are made identically and the oversizedholes in the brackets allow for some adjustment in the position ofbracket 484 as described later.

A worm gear 520 is mounted at the other end of short shaft 482, as shownin FIG. 18. Worm gear 520 meshes with a worm 522 that is mounted at theend of an elongate shaft 524. Shaft 482 allows shaft 524 to bepositioned optimally, as explained later. In alternative configurations,shaft 482 and pinion gear 480 may be eliminated and worm gear 520positioned in the place of pinion gear 480 so that it may drive threadedrod 460 directly when worm 522 turns, as shown in FIG. 19. Worm 522slides onto the end of shaft 524 and a bolt 523 passes through a washerand threads into a hole at the end of the shaft. A slot in shaft 524holds a woodruff key that keeps the worm from rotating about the shaft.The worm is mounted in this way because it needs to be attached to shaft524 after the shaft passes through secondary torque tube 262 whichsurrounds the shaft. Mounting the pinion gear, worm gear 520 and worm522 behind the rear trunnion helps to minimize the dust that wouldotherwise build up on them.

It is important to be able to adjust the vertical position of worm gear520 in order to maintain the mesh between the worm gear and the worm.Hole 500, into which the positioning pin on the back of bracket 484 isinserted, has an oval shape to allow the vertical position of bracket484 to be adjusted. A set screw 526 threads vertically down through ahole 528 in a cubed extension 530 which extends outward from the back ofthe rear trunnion, as shown in FIG. 18. The threaded end of the setscrew presses against the top of bracket 484. The inset head of the setscrew is exposed so that the set screw can be adjusted. The farther theset screw is screwed into the hole, the farther bracket 484 is pusheddownwards.

Shaft 524 passes through a set of flanged bushings fitted into the frontand back of a bore 536 (best seen in FIG. 9) in the rear trunnion. Shaft524 then passes through the hollow center of secondary torque tube 262which extends from the rear trunnion to the front trunnion bracket andencloses shaft 524. Shaft 524 then passes through a collar 538 (shownbest in FIG. 28) which is bolted to torque tube 262 and which holdsshaft 524 in place. Shaft 524 extends out through the curved slot 378 inthe front of cabinet 104 and a handwheel 112 is mounted on the shaft.When a person turns handwheel 112 and shaft 524, worm 522 causes wormgear 520 to turn, which rotates shaft 482 and causes pinion gear 480 toturn. When pinion gear 480 turns, it crawls along threaded rod 460causing elevation plate 380 to move up or down. Moving the elevationplate up and down causes the blade to move up and down relative to thetabletop. In this manner, a user may adjust the elevation of the blade.

Once the elevation of the blade is adjusted, handwheel 112 is locked sothat it cannot accidently be turned. The locking mechanism used to lockthe handwheel includes a hole 560 at the end of shaft 524 adjacenthandwheel 112 which runs along the longitudinal axis of the shaft fromthe handwheel to collar 538 as shown by the dotted lines 561 in FIG. 20.A section of the hole closest to the end of the shaft is threaded andthe rest is not. A long pin 562 with a threaded section at one end isattached at the threaded end to a knob 564. Pin 562 passes through thecenter of the handwheel and is threaded into hole 560, but notcompletely. The tip of pin 562 reaches the side of a woodruff key 566which is shaped like a semi-circle and which sits in a semicircular slot568 in shaft 524. The woodruff key and slot are positioned under collar538 so that as knob 564 is turned such that pin 562 threads farther intothe hole, pin 562 pushes against the side of the woodruff key forcingthat end of the woodruff key upwards against the inside wall of collar538. By turning knob 564, the woodruff key can be wedged between collar538 and shaft 524 strongly enough to keep shaft 524 from turningrelative to collar 538 thus locking handwheel 112, and thus elevationplate 380, in place. A similar mechanism is used to lock the tilthandwheel 114 in place except that the woodruff key is located in abushing 348.

The construction of elevation plate 380 and shafts 390 and 398 may bereferred to as a vertical slide because the elevation plate slidesvertically on the shafts. Other constructions of vertical slides arealso possible, such as using one or move dovetail slides or rectangularslides instead of shafts.

Additionally, a motor may be used instead of handwheel 112 to turn thegears necessary to raise or lower the elevation plate, or a motorizedlift may be used instead of gears. The motor or lift may be actuated bya typical switch or by a switch configured to be similar to a handwheel.Similarly, a motor could be used instead of the handwheel 114 to controlthe tilt of the trunnions.

Elevation plate 380, and any components attached to the elevation plate(such as a motor, as will be discussed below), may have significantweight and therefore it may be difficult to turn handwheel 112 to raisethe blade. Accordingly, the depicted embodiment includes a gas spring580 mounted at one end to the left side of the elevation plate by bolt582, as shown in FIG. 28. The other end of gas spring 580 is bolted to abracket 584, which in turn is bolted to the bottom of shaft 390. The gasspring is positioned near the side-to-side center of gravity of all theparts supported by the elevation plate and is biased to push theelevation plate up with a predetermined amount of force to make it easyfor a user to turn handwheel 112 to raise the blade. The force of thegas spring may be selected so that the elevation plate is biased up ordown. Forces in the range of 60 to 100 pounds may be used, depending onhow much weight must be lifted.

An alternative elevation mechanism is shown in FIG. 21. In thisimplementation, a cable 586 and spool 588 are used in place of athreaded rod and pinion gear to raise and lower the elevation plate.Cable 586 is a thick wire cable capable of supporting the weight of themotor, elevation plate and everything attached to the elevation plate.Cable 586 is wound once around a spool 588 and is kept taut with eachend of the cable fixed to each end respectively of an iron bar 590 thatis vertically oriented. The tension in the cable can be adjusted bysecuring the ends of the cable to the iron bar with eye-bolts 591, forexample, which can be threaded into or out of bores in the iron bar.Iron bar 590, in turn, is either attached to the side of elevation plate380 by bolts or a weld, or may form part of the elevation plate itself.A small, rectangular metal plate 592, shown best in FIG. 22, is attachedto spool 588 by two screws 594. Cable 586 fits within a groove 596located between the two screws on the side of the plate that faces thespool. The cable is sandwiched between the plate and the spool to keepit from sliding on the spool as the spool rotates. Spool 588 is attachedto one end of shaft 482 and the other end of the shaft is attached toworm gear 520. As the worm turns the worm gear, spool 588 rotates andcauses the position of the cable winding around the spool to changeposition relative to and along the length of the cable. Because thespool is at a fixed location in the saw, the iron bar 590 to which thetwo ends of the cable is attached is forced up or down depending onwhich way spool 588 rotates. When the top of spool 588 rotates towardthe front of the saw, cable 586 pulls the top end of iron bar 590downward. When the top of spool 588 rotates away from the front of thesaw, cable 586 pulls the bottom end of iron bar 590 upwards. As iron bar590 moves up and down, the elevation plate and all attached to it movesup and down, sliding on the primary and secondary elevation shafts. FIG.21 shows the elevation plate in a lowered position and FIG. 23 shows theelevation plate in a raised position. Spool 588 is sized such that thespool need only rotate about half a revolution in order for theelevation plate to move through the full range of vertical motionnecessary. Plate 592 is fixed to the spool at a location that allows thespool to rotate without interference from the plate hitting the verticalstretch of cable. An alternative configuration may use a chain 598 andsprocket 599 in place of a cable and spool. The chain may be orientedvertically and contact the sprocket for a varying length along thesprocket, one example of which is shown in FIG. 24, or it may wraparound the sprocket, as shown in FIG. 25. Still other configurations mayuse miter or bevel gears instead of a worm or worm gear in the elevationmechanism.

An arbor block 600 is pivotally mounted to the elevation plate as shownin FIGS. 26 and 28. The arbor block includes two projections 602 and604, each projection having a bore 606, as shown in FIG. 27. Theelevation plate includes a support flange 608 and a bore 610 extendsthrough that support flange, as shown in FIG. 14. Projections 602 and604 on the arbor block sandwich support flange 608, and a shaft 612passes through bores 606 in the arbor block and bore 610 in theelevation plate to mount the arbor block to the elevation plate. Arborblock 600 may then pivot up and down around shaft 612.

An arbor 614 is mounted for rotation in arbor block 600, as shown inFIG. 26, and the blade of the saw is mounted on the arbor along with ablade washer 615 and blade nut 616 so that it spins when the arborrotates, as shown in FIGS. 33 and 34. The arbor is held in two bearingsthat are mounted in bearing seats in the arbor block. The bearings areisolated electrically from the arbor block by plastic overmolding on thearbor or by insulating bushings. Electrodes are positioned adjacent butnot touching the arbor to impart the electrical signal to the blade usedin the detection subsystem discussed above. The configuration ofpossible arbors and electrodes are disclosed in detail in U.S. PatentApplication Publication Nos. 2005/0039822 A1 and 2007/0101842 A1, bothtitled “Woodworking Machines With Overmolded Arbors,” the disclosures ofwhich are hereby incorporated by reference.

Shaft 612 extends outwardly to the right of the arbor block a sufficientdistance so that a brake cartridge 617 may be pivotally mounted on theshaft, as shown in FIG. 34. The brake cartridge is sized and positionedso that it is adjacent the perimeter of a blade having a specifiednominal diameter. The brake cartridge includes a pawl, and the pawlpivots toward the blade around shaft 612 to stop the blade from spinningwhen the detection subsystem detects that a person has contacted theblade, as described above. The brake cartridge may be constructed andmounted in the saw in many ways. Examples of how the brake cartridge maybe constructed and mounted in a saw are disclosed in U.S. PatentApplication Publication No. 2005/0039586 A1, entitled “Brake Cartridgesfor Power Equipment,” and U.S. Patent Application Publication No.2005/0139058 A1, entitled “Brake Cartridges and Mounting Systems forBrake Cartridges,” the disclosures of which are hereby incorporated byreference. Those publications also disclose how the position of thebrake cartridge relative to the perimeter of the blade may be adjustedby a linkage between the arbor block and the mounting structure for thebrake cartridge. Arbor block 600 includes an aperture 618 through whicha bolt 620 may extend to adjust the spacing between the brake cartridgeand the blade.

Brake cartridge 617 also acts as a mechanism to prevent a user of thesaw from installing a blade larger than recommended. The brake cartridgephysically blocks a large blade from being mounted on the arbor becausethe blade bumps into the brake cartridge.

A cylindrically-shaped retraction pin 630 (shown in FIG. 27) rests in arecess in a side of arbor block 600 near arbor 614 so that the pin issubstantially horizontal and so that the surface of the pin extendsbeyond the side of the arbor block. Retraction pin 630 engages an arborblock support mechanism to hold the arbor block up and prevent the arborblock from pivoting around shaft 612 during normal operation of the saw.However, when a person accidentally contacts the blade the brakecartridge will engage and stop the blade. The angular momentum of theblade as it is stopped will create a significant downward force and thatforce will cause retraction pin 630 to disengage from the arbor blocksupport mechanism. When the retraction pin has disengaged, the arborblock will be free to pivot around shaft 612, so the downward forceresulting from stopping the blade will cause the arbor block to pivotdown very quickly. The blade will also pivot down because the blade issupported by the arbor block. In this manner, the blade will retractbelow the tabletop of the saw when a person accidentally contacts theblade.

In the depicted embodiment, the arbor block support mechanism takes theform of a flat, roughly rectangular shaped retraction bracket 634 boltedto the elevation plate, as shown in FIG. 28. Bolts 636 and 638 passthrough holes in the retraction bracket and thread into correspondingholes 640 and 642 in the elevation plate. The retraction bracket isshaped so that the bolts are spaced apart in such a way as toaccommodate the torque necessary to support arbor 614, although othershapes are possible. Retraction bracket 634 extends from the elevationplate toward arbor 614 and forms a type of leaf spring that is thickenough to support the arbor but thin enough to flex slightly. Retractionbracket 634 has a small, rectangular cutout 646 shaped to fit around pin630 so that the rounded outer surface of the pin protrudes into thecutout. By protruding into the cutout, pin 630 holds the end of thearbor block in place and prevents the arbor block from retracting.Retraction bracket 634 also includes a curved slot 656 and a bolt 648passes through a washer 650, through a spring 652, through anotherwasher 654, and then through the curved slot to thread into hole 658 inthe left side of arbor block 600. Spring 652 exerts a force againstretraction bracket 634 to keep the retraction bracket adjacent the arborand surrounding pin 630. However, when the brake cartridge activates tostop the blade, the downward force caused by the angular momentum of theblade will overcome the force of spring 652 and retraction pin 630 willthen push retraction bracket 634 aside and move down with the arborblock as the arbor block pivots downward about shaft 612. Curved slot656 runs generally vertically and allows bolt 648 to move downward asarbor block 600 pivots downward. The stronger the force that the spring652 exerts, the harder it is to disengage the retraction pin 630 fromcutout 646 in the retraction bracket. This force can be adjusted byturning bolt 648.

A bracket 682 is mounted on secondary torque tube 262 and furthersupported by vertical plate 268. The bracket is positioned below arborblock 600, as shown in FIG. 28, and a bumper or pad 680 is mounted upona corner of the bracket. When the arbor block retracts, bumper 680 stopsthe downward motion of the arbor block and helps absorb the energy ofthe retraction. The arbor block includes a surface 684 configured tocontact bumper 680, as shown in FIG. 28.

The energy of retraction may be significant. Accordingly, bumper 680 maybe selected from materials that have good dampening characteristics andarbor block 600 may be made from a ductile iron so that the arbor blockit is less likely to be damaged during retraction. Additionally, torquetube 262 should be constructed so that it is sufficiently strong tosupport bumper 680 and withstand the force of impact with the arborblock, and it is positioned low in the saw to provide clearance for thearbor block and blade to retract.

In some embodiments, bumper 680 and surface 684 may act as a stop tolimit the downward motion of the elevation plate, and in thoseembodiments, they would take the place of stop 422, bolt 432 andshoulder 434 discussed previously.

Alternative configurations of arbor block 600 and retraction bracket 634allow the user to adjust the angle at which the arbor block rests whenit is supported by the retraction bracket. FIG. 29 shows an alternativearbor block 686 in which retraction pin 630 has been replaced by acustom bolt 688 with a square head. Bolt 688 is shown isolated in FIG.30. Each side 690 of the square head is rounded like retraction pin 630and is shaped to fit within cutout 646 in the retraction bracket tosupport the arbor block. In this alternative configuration, retractionbracket 692 is similar to retraction bracket 634, except the bottomcorner below curved slot 656 is removed, as shown by arrow 694 in FIG.31. Removing the bottom corner of the retraction bracket allows bolt 688to clear the bottom of the bracket when the arbor block is retracted sothat bolt 688 can be turned. Turning the bolt so that it threads fartherinto or out of the arbor block changes the angle at which the arborblock rests when supported by the retraction bracket. The spacing of thethreads on the bolt determines the distance the bolt will travelvertically with each quarter turn of the bolt.

Saw 100 is powered by a motor 700 mounted to the front of elevationplate 380. The motor may be mounted to the elevation plate in many ways.In the depicted embodiment, tabs 702, shown in FIG. 32, project out fromthe motor and sandwich a projection 704 on the front of the elevationplate (projection 704 is labeled in FIG. 28). Bolts 706 and 708, shownin FIG. 33, pass through corresponding holes 710 in the tabs and throughoversized holes 712 in the projection. The bolts are then secured withnuts 714 which are welded to the motor tab so only one wrench is neededto install the bolts. Thus, the motor can be mounted to the elevationplate, as shown in FIGS. 33 and 35, by one person with one hand to befree to hold the motor while the other hand tightens bolts 706 and 708.

Tabs 702 on motor 700 are positioned to the side of the motor so thatthe motor attaches to the elevation plate in such a way that theside-to-side center of gravity of the motor together with all the otherparts supported by the elevation plate falls near shaft 390 and threadedrod 460 which support the elevation plate. Threaded rod 460 ispositioned near elevation shaft 390 in order to minimize the torque,that is, the rotating force on the elevation shaft. Ideally, shaft 524of handwheel 112 would extend from the bottom of the threaded rod out tothe front of the cabinet. However, this would mean that shaft 524 wouldneed to go through the motor and, even so, the position of handwheel 112would not be optimal. Shaft 524 of handwheel 112 should be located sothat handwheel 112 is towards the center of the front of the cabinet andsufficiently below the table so that users can turn the handwheelwithout hitting their knuckles on the underside of the table.Additionally, because shaft 524 moves with the trunnions as they tilt,it should be positioned below shaft 332 of tilt handwheel 114 so that itclears front trunnion bracket 140. The presence of shaft 482 and thepositioning of worm gear 520 and worm 522 behind the rear trunnionbracket allow flexibility in choosing the placement of handwheel 112.Both the handwheel and the threaded rod 460 can be placed in the optimalpositions and the length of shaft 482 sized accordingly.

The motor drives arbor 614 through a two-belt system. A short shaft 736is bolted at one end to the front of the elevation plate by a bolt 738which passes through a washer 739 and a hole 740 in shaft 736, as shownin FIG. 32. Bolt 738 then threads into a hole 741 in the elevation platewhich can best be seen in FIG. 28. The end of shaft 736 opposite hole740 has a small protrusion of a slightly smaller diameter that isconfigured to fit within a hole 740 in retraction bracket 634. A doublepulley 734 is mounted on shaft 736 between the ends of the shaft. Thedouble pulley includes an inner belt track adjacent retraction bracket634 and an outer belt track. The motor has a drive shaft 730 and a motorpulley 732 is mounted on the drive shaft. A first belt 742 extendsaround the motor pulley and the inner belt track of the double pulley.An arbor pulley 744 is mounted on the end of arbor 614, opposite theblade, and a second belt 746 extends around arbor pulley 744 and theouter track of double pulley 734. Motor 700 turns pulley 732, which thenturns double pulley 734 and arbor pulley 744, causing the blade mountedon the arbor to spin. Shaft 736 is offset slightly from shaft 612 aboutwhich the arbor block pivots so that when the arbor block retracts, belt746 is slightly loosened. This allows the belt to be changed moreeasily. Offsetting the axis of shaft 736 from the axis of shaft 612 alsoallows belt 746 to slip when the brake cartridge stops the blade and thearbor block retracts, which possibly allows the blade to stop morequickly and which helps prevent polishing or other damage to the belt ifthe motor continues spinning for a short period of time after the bladestops.

Shaft 736 can be removed as necessary for changing belts by removingbolt 738 and slipping it out of the retraction bracket. Pulleys 734 and744 are fixed-center pulleys, so a slightly stretchy Poly-V beltdesigned for fixed center pulleys is used. A slightly stretchy belt hasthe advantage of being able to stretch to meet manufacturing tolerances.The depicted embodiment includes a double belt system as described sothat arbor block 600 may retract by pivoting down around shaft 612without disengaging from the drive belts.

The belt around pulley 744 is preferably made of a static dissipativematerial so that static charge does not build up on the arbor or blade.This is advantageous because in some implementations a static charge mayinterfere with the detection subsystem. The pulleys may be sized so thatthe blade spins at a desired speed, such as 4000 rpm, while the motorspins at a different speed, such as 3450 rpm.

The belt extending around the motor pulley and the inner track of doublepulley 734 may be tensioned by adjusting the position of the motor. Asmentioned earlier, motor 700 is mounted to the elevation plate by twobolts which pass through oversized holes 712 in the elevation plate. Theoversized holes allow some flexibility in the vertical position of themotor. To put tension on the belt, bolts 706 and 708 are loosened andthe motor is moved up or down, that is, closer to or farther from thedouble pulley, until the belt is at the right tension. When the desiredtension is achieved, the bolts are tightened to hold the motor inposition.

In an alternative configuration, the motor may drive arbor 614 directlythrough a one-belt system, as shown in FIG. 36. In this configuration,belt 800 wraps around motor pulley 732 and arbor pulley 744, and themotor is positioned to keep some tension on the belt when the arborretracts.

Saw 100 may include a shroud shaped to partially enclose the blade undertable 102. Shrouding the blade prevents a person from contacting theblade under the table. This is useful because if a person contacts theblade under the table, the brake cartridge will fire and the blade willretract, possibly into the person's hand. Shrouding the blade also helpsto collect sawdust created when the saw is running.

A dust port 850 is shown on the back of the cabinet in FIG. 38 and isshown isolated in FIGS. 37A, 37B and 37C. FIG. 37B shows a front view ofthe dust port and FIG. 37C shows a side view of the dust port. The dustport consists of a front tube 852 which extends out from the saw, and aback tube 854 which extends into the saw. A flange 856 spans around themiddle of the tubes and extends outward. Flange 856 is used to mount thedust port to the saw. The flange includes three holes 858 withcorresponding bosses 860 formed on the backside of the flange. Thebosses are designed to accommodate thread-forming fasteners. Duringassembly, the dust port is carried inside the cabinet and front tube 852is inserted through a hole in the back of the cabinet. Three small holes862 are positioned in the cabinet to align with holes 858 in the dustport flange, and fasteners or screws pass through holes 862 and 858 andthread into bosses 860 to mount the dust port to the cabinet. A smallsemicircle 864 protrudes on the backside of flange 856 and functions asa key to easily orient the dust port so that the three bosses on thedust port line up with the three holes in the cabinet. Because the dustport is a separate part from the cabinet, a user can choose to install adust port with front tube 852 having either a four inch or two inchouter diameter, depending on the dust collection system that will beattached to the dust port.

The cabinet of the table saw may include openings to allow access to theinternal mechanism of the saw. FIG. 3 shows saw 100 with a cover 900over such an opening. The cover is designed to fit around the motor, asshown in FIG. 38, taking into account that the position of the motorwill change as the blade tilts. Cover 900 is mounted to the cabinet witha hinge so it can pivot open, as shown in FIG. 4. The hinge iseffectively a pin-and-barrel type of hinge comprised of a row ofalternating half-cylinders 902 integrated along the back edge of theplastic cover, a metal rod 904, and two short metal tubes 906 welded,screwed, or otherwise attached to the side of the cabinet. Rod 904slides through the lower metal tube 906, through the alternatinghalf-cylinders 902 and then through the upper metal tube 906, as shownin FIG. 39. An L-shaped hook 910 is integrated into the plastic cover,as shown in FIG. 40, and is positioned just below the lower metal tube906. Rod 904 has a bent end 912 which can be rotated and positionedwithin hook 910 so that the rod is held in place. The hinge is designedso that it has only a few parts and so that it can easily be assembledwithout the need of extra tools. A latch 914, shown in FIG. 41, isintegrated on the front of cover 900 to keep the cover closed. The latchincludes an area 916 along the middle of the front edge of cover 900that provides a place for a hand to press upon. Area 916 is set apart bytwo notches 918 and 920 cut horizontally inward from the edge of thecover to relieve stress, and it has ribs 922 for strength. Area 916extends past the edge of cover 900 and bends to form a lip 924, shown inFIGS. 41 through 43, to catch the inner edge of the cabinet in order tokeep the cover closed. Lip 924 is made stronger by having a triangularshape, as shown at 926 in FIG. 43. The cover can be opened by pressingupon area 916 which flexes area 916 inward and moves lip 924 out frombehind the cabinet edge so that the cover is free to pivot open. Toclose and latch the cover, the user presses upon area 916 so that thetriangular shape of lip 924 engages the edge of the cabinet. The slopeof the side of the triangular shape helps cause area 916 to flex inwardas the cover is pushed towards the cabinet. Once the lip is past theedge of the cabinet, it snaps into place behind the edge, thus latchingthe cover closed. An extension 928 at the base of the cover fits into acorresponding rectangular slot 930 in the cabinet to help align thecover to the cabinet.

Cover 900 is made of a rigid material, such as plastic or metal, and mayinclude louvers to allow airflow into the cabinet. A flange 932, bestseen in FIGS. 39 and 42, runs along the outside edge of the cover. Thecover may be designed so that when it is closed, there is a small gapbetween flange 932 and the cabinet to reduce noise that could otherwiseresult from the vibration of the saw. In order to reduce noise caused byvibration in the area where the motor cover latches to the cabinet, foammay be placed on the underside of flange 932 above and below latch 914as indicated by arrows 934 in FIG. 41. Flange 932 continues around area916, as shown, to provide strength and rigidity around the area.

Saw 100 also includes a switch box 950 with one or more switches tocontrol the operation of the saw. A switch box designed for use withsafety systems as described above is described in detail in U.S. PatentApplication Publication No. 2005/0139459 A1, entitled “Switch Box forPower Tools with Safety Systems,” the disclosure of which is herebyincorporated by reference.

Saw 100 may also come with a fence 952 that rests on table 102 andclamps to a front rail. The fence provides a face against which a usermay slide a work piece when making a cut. One possible fence isdisclosed in U.S. Patent Application Publication No. 2005/0139046 A1,entitled “Fences for Table Saws,” the disclosure of which is herebyincorporated by reference.

Saw 100 may also come with a riving knife. A riving knife sits behindthe blade and functions to prevent a work piece from engaging the teethat the back of the blade. As a work piece is cut into two sections, thenewly cut sections may flex or move. If one of the newly cut sectionsmoves to the side and catches the back edge of the spinning blade, theblade may suddenly kick the work piece back toward the user at a veryhigh speed and the user's hand may be pulled into the blade by thesudden movement of the work piece. The riving knife impedes the workpiece from moving to the side and thereby minimizes the chance of thework piece catching the back edge of the blade. The riving knife alsominimizes the chance of newly cut sections of a work piece movingtogether and binding the blade. One possible riving knife and systems tomount the riving knife in the saw are disclosed in U.S. PatentApplication Publication No. 2005/0166736 A1, entitled “Table Saws WithSafety Systems and Systems to Mount and Index Attachments”, thedisclosure of which is hereby incorporated by reference.

The saw may also come with a blade guard, miter gauge and bladewrenches.

INDUSTRIAL APPLICABILITY

The systems, mechanisms and components disclosed herein are applicableto power equipment, and particularly to table saws, including cabinetsaws, contractor saws, hybrid saws, jobsite saws, and bench top saws.

It is believed that the disclosure set forth above encompasses multipledistinct inventions with independent utility. While each of theseinventions has been disclosed in its preferred form, the specificembodiments thereof as disclosed and illustrated herein are not to beconsidered in a limiting sense as numerous variations are possible. Thesubject matter of the inventions includes all novel and non-obviouscombinations and sub-combinations of the various elements, features,functions and/or properties disclosed herein. No single feature,function, element or property of the disclosed embodiments is essentialto all of the disclosed inventions. Similarly, where the claims recite“a” or “a first” element of the equivalent thereof, such claims shouldbe understood to include incorporation of one or more such elements,neither requiring nor excluding two or more such elements.

It is believed that the following claims particularly point out certaincombinations and sub-combinations that are directed to one of thedisclosed inventions and are novel and non-obvious. Inventions embodiedin other combinations and sub-combinations of features, functions,elements and/or properties may be claimed through amendment of thepresent claims or presentation of new claims in this or a relatedapplication. Such amended or new claims, whether they are directed to adifferent invention or directed to the same invention, whetherdifferent, broader, narrower or equal in scope to the original claims,are also regarded as included within the subject matter of theinventions of the present disclosure.

1. A table saw comprising: a table to support a workpiece; a bladeextending at least partially through the table to cut a workpiece on thetable; and an elevation mechanism configured to adjust the height of theblade relative to the table, where the elevation mechanism includes twospaced-apart shafts behind the blade and an elevation carriage adaptedto move on the shafts.
 2. The table saw of claim 1, where the table hasa front and a rear, where the blade has a perimeter, where the perimeterof the blade closest to the rear of the table is the rear of the blade,and where the two spaced-apart shafts are between the rear of the bladeand the rear of the table.
 3. The table saw of claim 1, where the bladeis substantially planar and where the two spaced-apart shafts arepositioned to define a plane substantially perpendicular to the plane ofthe blade.
 4. The table saw of claim 1, where the two spaced-apartshafts are positioned so that one shaft is to one side of the blade andthe other shaft is to the other side of the blade.
 5. The table saw ofclaim 1, further comprising a trunnion structure, and where the twospaced-apart shafts interconnect the elevation carriage and the trunnionstructure.
 6. The table saw of claim 1, further comprising a trunnionstructure, and where each of the two spaced-apart shafts is fixed to thetrunnion structure.
 7. The table saw of claim 6, where at least one ofthe two spaced-apart shafts is fixed to the trunnion structure by twospaced-apart bolts.
 8. The table saw of claim 6, where each of the twospaced-apart shafts is fixed to the trunnion structure by twospaced-apart bolts.
 9. The table saw of claim 1, where the elevationcarriage contacts at least one of the two spaced-apart shafts at twospaced-apart locations.
 10. The table saw of claim 1, where theelevation mechanism further comprises a threaded shaft positionedadjacent one of the two spaced-apart shafts behind the blade.
 11. Thetable saw of claim 10, where the threaded shaft is supported by theelevation carriage.
 12. The table saw of claim 10, where the blade issubstantially planar, where the two spaced-apart shafts are positionedto define a plane substantially perpendicular to the plane of the blade,and where the threaded shaft is positioned substantially in the plane ofthe two spaced-apart shafts.
 13. A table saw comprising: a table tosupport a workpiece; a blade extending at least partially through thetable to cut a workpiece on the table; and an elevation mechanismconfigured to adjust the height of the blade relative to the table,where the elevation mechanism is positioned in the saw downstream of theblade.
 14. A table saw comprising: a table to support a workpiece; ablade extending at least partially through the table to cut a workpieceon the table; and an elevation mechanism configured to adjust the heightof the blade relative to the table, where a user applies a force tooperate the elevation mechanism, and where the elevation mechanismincludes a structure to shift the point of application of the force. 15.The table saw of claim 14, where the elevation mechanism includes ahandwheel and handwheel shaft, where the user applies a force to operatethe elevation mechanism by turning the handwheel, and where thestructure to shift the point of the application of the force includes atransfer shaft to transmit the force from the handwheel shaft to anotherposition in the saw.
 16. A table saw comprising: a table to support aworkpiece; a blade able to extend at least partially through the tableto cut a workpiece on the table; an arbor block adapted to support theblade and pivot downward relative to the table around a pivot axis toretract the blade; and a drive mechanism to spin the blade, where thedrive mechanism includes a motor, a motor pulley, a double pulley, anarbor pulley, a first belt extending around the motor pulley and doublepulley, and a second belt extending around the double pulley and arborpulley, where the double pulley is supported in the saw to rotate aroundan axis offset from the pivot axis.